18 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
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Your boiler is attempting to start but failing to stay lit, which means it cannot provide heat or hot water.
Your boiler is currently in standby mode because it is not receiving a signal from your thermostat or timer to turn on your heating or hot water.
Your boiler has failed to start after three attempts, likely because it is struggling to find a stable gas supply or has air trapped in the system.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler has stopped working because it failed to ignite, which means it is currently unable to provide you with any heating or hot water.
Your boiler has detected a flame when it should not be burning, which indicates an internal component failure rather than a normal heating operation.
Your boiler is operating normally and is currently heating your water or home as requested.
Your boiler is operating exactly as it should and the green light indicates the burner is currently lit and heating your water.
Your boiler has stopped working for safety reasons and has locked itself to prevent starting until a professional technician can investigate the internal fault.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low.
Your boiler is currently in a setup or testing mode and is not reporting an actual fault.
Your boiler is receiving a constant electrical signal telling it to run, which prevents it from properly starting or finishing its normal heating cycle.
Your boiler has stopped working for safety reasons and needs to be manually restarted to begin its ignition sequence again.
Your boiler has detected that the electrical supply wires have been connected in the wrong order, which means it cannot safely operate until the wiring is corrected.
Your boiler has detected that the electrical wiring supplying it is connected backwards, which prevents it from operating safely.
Your boiler is currently receiving a signal to turn on and is performing a status check of its electrical system during set-up or normal operation.
Your boiler has correctly received a signal from your thermostat or timer and is successfully starting the heating process as requested.
Your boiler is correctly receiving a signal from your thermostat that it needs to turn on, so this light simply indicates that your heating or hot water is currently in active mode.
BoilerFaultCodes